1. Field of the Invention
The present invention relates to the field of high speed circuits, and more particularly, to a method for producing an electrical connection to a high temperature superconductor (HTS) circuit.
2. Description of the Prior Art
Methods for producing electrical connections to electrical circuits are generally known in the art. Typically, solder bumps have been used to provide electrical connections for various electrical circuits. For this technique, a solder bum is placed on top of an electrical contact disposed on a chip or electrical circuit. The solder bump is then physically joined to another solder bump located on a second circuit to provide electrical connections between the two circuits. This method has been successful when used on chips or circuits which can handle the heat associated with applying a typical solder bump. It has not however been successful with high temperature superconductor (HTS) circuits because the heat associated with the solder bump process damages the HTS circuit.
Heating of the HTS circuit results in the HTS circuit losing oxygen, which oxygen is required for the HTS circuit to be conductive. Applying a solder bump in the typical fashion to an electrical contact on the HTS circuit results in the HTS circuit being heated which results in decreased conductivity of the HTS circuit thereby damaging the HTS circuit.
Since the current method of attaching solder bumps to an electrical circuit can not be used to provide an electrical contact to HTS circuits, wirebonding or pin connections have been used instead. Wirebonding and pin connections do not require elevated temperatures and therefore can provide an electrical connection to HTS circuits without damaging the HTS circuit. Although wirebonding provides a good electrical connection, it has a number of disadvantages. At high frequencies, inductance occurs between the wires which can change the electrical characteristics of the HTS circuit. In addition, wires require a significant amount of space on an HTS circuit.
A method therefore is needed to provide an electrical connection to an HTS circuit that minimizes oxygen loss in the HTS circuit, does not add inductance at high frequencies; and, requires a small amount of volume on the HTS circuit.